C.  Grazianetti, De Rosa, S., Martella, C., Targa, P., Codegoni, D., Gori, P., Pulci, O., Molle, A., and Lupi, S., ?Optical Conductivity of Two-Dimensional Silicon: Evidence of Dirac Electrodynamics?, Nano Letters, vol. 18, pp. 7124-7132, 2018.